www.nature.com/scientificreports OPEN Mineral analysis reveals extreme manganese concentrations in wild harvested and commercially available edible termites Rudi L. Verspoor1*, Murielle Soglo2, Razack Adeoti2, Rousseau Djouaka2, Sam Edwards1, Rikard Fristedt3, Maud Langton 4, Rosana Moriana4, Matthew Osborne 5, Catherine L. Parr6,7,8, Kathryn Powell1, Gregory D. D. Hurst1 & Rikard Landberg3 Termites are widely used as a food resource, particularly in Africa and Asia. Markets for insects as food are also expanding worldwide. To inform the development of insect-based foods, we analysed selected minerals (Fe-Mn-Zn-Cu-Mg) in wild-harvested and commercially available termites. Mineral values were compared to selected commercially available insects. Alate termites, of the genera Macrotermes and Odontotermes, showed remarkably high manganese (Mn) content (292–515 mg/100 gdw), roughly 50–100 times the concentrations detected in other insects. Other mineral elements occur at moderate concentrations in all insects examined. On further examination, the Mn is located primarily in the abdomens of the Macrotermes subhyalinus; with scanning electron microscopy revealing small spherical structures highly enriched for Mn. We identify the fungus comb, of Macrotermes subhyanus, as a potential biological source of the high Mn concentrations. Consuming even small quantities of termite alates could exceed current upper recommended intakes for Mn in both adults and children. Given the widespread use of termites as food, a better understanding the sources, distribution and bio-availability of these high Mn concentrations in termite alates is needed. Insects are consumed as food in many countries around the world. Much of this consumption derives from cultural traditions of entomophagy, particularly in Africa, south-east Asia, and central America1,2. Marketing and export of edible insects can also provide an important source of revenue (e.g.3) and the use of insects as food is expanding into countries beyond those where use is traditional. As a result, edible insects now attract global attention in research, media and commercial sectors; particularly with respect to their contribution to food secu- rity and sustainability4,5. Te expanding market of edible insects creates challenges in terms of regulation and quality control6. Novel edible insects are reaching new markets, bringing unique obstacles for value chain regulation; for example accu- rate identifcation of species. Specifc factors, such as wild harvesting and rural processing bring additional dif- culties when trying to establish and maintain the quality of insect foods6,7; for example, the accumulation of heavy metals8,9. However, the extent and source of variations in mineral content within and between species remains largely unknown. Tis knowledge gap is important, as nutritional information underpins food safety standards and is vital for decision making when novel foods are entering markets, for example in the European Union10. Termites, in particular winged termites (henceforth referred to as ‘alates’), are widely consumed in quantity as food across Africa, America and Asia1,11,12 when they emerge en masse during the rainy season. Worldwide it is reported that 43 species are used as either human or livestock feed, with some species, particularly those from the genus Macrotermes, most commonly used as human food12. A number of studies on alates as food have highlighted 1Institute of Integrative Biology, University of Liverpool, Liverpool, L69 7ZB, United Kingdom. 2IITA Research Station, Godomey, Benin. 3Chalmers University of Technology, Department of Biology and Biological Engineering, Division of Food and Nutrition Science, SE-412 96, Göteborg, Sweden. 4Swedish University of Agricultural Sciences, Department of Molecular Sciences, Box 7015, 750 07, Uppsala, Sweden. 5Stockholm Environment Institute, Stockholm, Sweden. 6School of Environmental Science, University of Liverpool, Liverpool, L69 3GP, United Kingdom. 7Department of Zoology & Entomology, University of Pretoria, Pretoria, South Africa. 8School of Animal, Plant and Environmental Sciences, University of Witwatersrand, Wits, South Africa. *email: [email protected] SCIENTIFIC REPORTS | (2020) 10:6146 | https://doi.org/10.1038/s41598-020-63157-7 1 www.nature.com/scientificreports/ www.nature.com/scientificreports Level reported Fe Zn Cu Mn Mg Lowest 0.14 (26) 0.21 (26) 0.03 (26) 0.08 (13) 0.15 (14) Highest 116 (14) 15 (18) 5 (18) 714 (18) 81 (18) RDA (Child 4–8) 10 5 0.44 * 1.5 * 130 RDA (Adult 18 8 0.9 1.8 320 female) * * RUL (Child 4–8) 40 12 3 3 110** RUL (Adult 45 40 10 11 350 female) ** Table 1. Example of highest and lowest reports of mineral contents for termites of the genus Macrotermes. Values are reported as mg/100g fresh weight. Numbers in parentheses indicate the studies referenced. Dietary advice values are presented as recommended daily allowance (RDA), and the recommended Upper Limit (RUL) in mg/day20,21. *values represent adequate intake (AI). **refers to magnesium in supplement form. their nutritional value and potential contribution to food security, both in raw and processed form13–15, due to the high protein and fat content of these insects16,17. Alates are also available in local and international markets, which provides local income and contributes to economic development16–18. In contrast to many farmed insects, alates are wild harvested, which could result in greater diferences between collections due to variation in diets, the species collected, and the local conditions. In some insects, including edible species, accumulation of minerals to toxic levels has been associated with environmental contamination8,9,19. In addition, there is a startling variation in trace minerals concentrations reported in studies examining alates (Table 1). Establishing consistent estimates of mineral concentrations in alates is critical when assessing their potential beneft and informing their potential marketability20,21. We examine the content of fve trace minerals (Fe-Mn-Zn-Cu-Mg) in a selection of alates from Benin and South Africa, where termites are commonly consumed as human food. We compare these concentrations of trace minerals to commercially available insects, including alate termites. Methods Insect material used for analysis. Field collection of edible termites. Alates of Macrotermes subhyalinus were collected from north-west Benin, where Macrotermes termites are consumed as food22. Termites were iden- tifed to species using classical taxonomy of termite soldiers collected from mounds in the area. Fungus comb, mound soil, and termite soldiers were also collected using a hoe from a subset of the mounds visited in the area around Tanguieta. Te samples were collected by hand around lights at dusk into a basin of clean water, between May and August 2017 and 2018. Te locations were within a 10 km radius of Tanguieta, Atakora department, Benin (Fig. 1Ai; Table S1). Samples therefore constitute a combination of alate termites from multiple mounds in a given area. We also collected samples of the large tobacco cricket (Brachytrupes membranaceus) from the same region in north-west Benin, by digging them out from their burrows using a hoe, to provide a second local edible insect species. Two further samples of alates were also collected from additional sites at Parakou (Borgou depart- ment, Benin), and from near Acornhoek (Mpumalanga, South Africa; Fig. 1A). In both these sampling locations termites are by communities. All samples were rinsed with clean bottled water afer collection to remove any mud or dust. Termites were then briefy sun-dried to remove external moisture and to assist with wing removal, a treatment that is traditional in Benin. Following wing removal then stored in food-grade storage containers at −20 °C or below until mineral analysis. For samples collected from South Africa, de-winged termites were oven dried at 60° overnight to allow for further transport at room temperature. Commercial insect types used. A selection of dried, processed edible insects were purchased from a supplier in the UK to provide a product comparison for the wild harvested termites (Table S1). Te commercial insects included both farmed insects and wild-harvested insects (including one sample of alate termites), multiple insect orders, and many widely consumed insect species. In particular, analysing commercially available alate termite and leaf-cutter ant queens provided a suitable reference comparison for our termites, and more widely to insects that use fungus farming for food. Single packets of each insect type were purchased and tested. To confrm the identity of the species being examined insects were barcoded23. Extraction and measurement of trace minerals. Sample transport and analysis. All mineral analysis was conducted at Chalmers University of Technology, Gothenburg unless stated otherwise. All termite samples from Benin were stored and transported fresh at −20 °C. Samples collected from Acornhuek in South Africa were dried and transported at room temperature. All commercial insects are delivered pre-dried and were then frozen and transported at −80 °C to Sweden from the UK. Upon arrival in Sweden all samples were stored at −80 °C. Moisture and total ash content for termite samples. Four replicates of fresh termites from north-west Benin were measured for total moisture and total ash content. To this end, 50 g of termites (de-winged) were freeze dried for a period of 72 hours. Tis was not possible to do with